Permanent magnet rotor with sinusoidal flux pattern

Abstract

A permanent magnet rotor wherein a rotary shaft has an orthogonal cross a sectional shape orthogonal in a longitudinal direction of the rotary shaft, a plurality of circular-arc portions which are around the axis of rotation of the rotary shaft, and rectilinear portions which connect the adjacent circular-arc portions with straight lines having no curved portion. Respective permanent magnets, equal in number to the circular-arc portions, are fixed extending over the circular-arc portions and the rectilinear portions. The surface of each permanent magnet remote from the rotary shaft has a cross sectional contour orthogonal to the longitudinal direction of the rotary shaft, forming a circular arc which protrudes outward.

What is claimed is: 
     
       1. A permanent magnet rotor including a rotary shaft means having an orthogonal cross-sectional shape in a longitudinal direction thereof comprising a plurality of circular-arc portions centered around an axis of rotation of said rotary shaft means, rectilinear portions for connecting adjacent circular-arc portions with straight lines having no curved portion, permanent magnets equal in number to said circular-arc portions fixed so as to extend over said circular-arc portions and said rectilinear portions in close contact therewith or at uniform intervals therefrom, an outer surface of each of said permanent magnets remote from said rotary shaft means having a cylindrical shape in a longitudinal direction of the rotary shaft means an inner surface of said permanent magnets adjacent to said rotary shaft means having a rectilinear portion and two circular-arc portions extending from a rectilinear portion, and wherein each of said permanent magnets is fixed to two of said circular-arc portions and one of said rectilinear portions located between the two circular-arc portions. 
     
     
       2. A permanent magnet rotor including a rotary shaft means having an orthogonal cross-sectional shape in a longitudinal direction thereof comprising a plurality of circular-arc portions centered around an axis of rotation of said rotary shaft means, rectilinear portions for connecting adjacent circular-arc portions with straight lines having no curved portion, permanent magnets equal in number to said circular-arc portions fixed so as to extend over said circular-arc portions and said rectilinear portions in close contact therewith or at uniform intervals therefrom, in outer surface of each of said permanent magnets remote from said rotary shaft means having a cylindrical shape in a longitudinal direction of said rotary shaft means, and an inner surface of said permanent magnets adjacent to said rotary shaft means having a circular arc portion and two rectilinear portions extending from the circular-arc portions, and wherein each of said permanent magnets is fixed to two of said rectilinear portions and one of said circular-arc portions located between the two rectilinear portions. 
     
     
       3. A permanent magnet rotor comprising mounting surfaces of permanent magnets shaped so as to have a plurality of small diameter circular-arc portions centered around an axis of rotation of a rotary shaft, gentle curve portions located between adjacent small-diameter circular-arc portions and being gentler in curvature than said small-diameter circular-arc portions, respective permanent magnets equal in number to said small-diameter circular-arc portions being fixed so as to extend over said small-diameter circular-arc portions and said gentle portions in close contact therewith or at uniform intervals, an inner surface of said permanent magnets adjacent to said rotary shaft means having a gentle curve portion and two small-diameter circular-arc portions extending from the gentle curve portion, and an outer surface of each of said permanent magnets remote from said rotary shaft having a sectional shape orthogonal to the axis of rotation of said rotary shaft in the form of an outwardly projecting circular arc. 
     
     
       4. A permanent magnet rotor comprising a rotary shaft means having a cross-sectional shape orthogonal to a longitudinal direction thereof including a plurality of outwardly projecting circular-arc portions and rectilinear portions for connecting the adjacent circular-arc portions with straight lines having no curved portion, respective permanent magnets equal in number to said circular-arc portions being fixed so as to extend over said circular-arc portions and said rectilinear portions in close contact therewith or at uniform intervals therefrom, and an outer surface of each of said permanent magnets remote from said rotary shaft means having a cylindrical shape in a longitudinal direction of said rotary shaft means, and wherein an inner surface of said permanent magnets adjacent to said rotary shaft means having a rectilinear portion and two circular-arc portions extending from the rectilinear portion. 
     
     
       5. A permanent magnet rotor comprising a rotary shaft means having an orthogonal cross-sectional shape in a longitudinal direction thereof including a plurality of circular-arc portions centered around an axis of rotation of said rotary shaft means and rectilinear portions for connecting the adjacent circular-arc portions with straight lines having no curved portion, respective permanent magnets equal in number to said circular-arc portions are fixed so as to extend over said circular-arc portions and said rectilinear portions in close contact therewith or at uniform intervals therefrom, and an outer surface of each of said permanent magnets remote from said rotary shaft means having a sectional shape orthogonal to the longitudinal direction of said rotary shaft means forming a circular arc, a center of which deviates toward said permanent magnet with respect to the axis of rotation of said rotary shaft means. 
     
     
       6. A permanent magnet rotor comprising a boss snugly fitted on a rotary shaft so as to prevent a turning thereof and having a sectional contour orthogonal to a longitudinal direction of said rotary shaft including a plurality of outwardly projecting circular-arc portions and rectilinear portions for connecting adjacent circular-arc portions with straight lines having no curved portion, permanent magnets equal in number to said circular-arc portions being respectively fixed so as to extend over said circular-arc portions and said rectilinear portions in close contact therewith or at uniform intervals therefrom, and an outer surface of each of said permanent magnets having a sectional shape orthogonal to the longitudinal direction of said rotary shaft forming an outwardly projecting circular arc, an inner surface of said permanent magnets adjacent to said rotary shaft means having a rectilinear portion and two circular-arc portions extending from the rectilinear portion.